U.S. Pat. No. 3,962,234 discloses and claims certain insecticidal esters of nitro(tetrahydro-2H-1,3-thiazin-2-ylidene)acetic acids, of the general formula ##STR1## wherein the symbol R has a defined meaning, and salts thereof. Those insecticidal esters are characterized by particularly high insecticidal activity with respect to caterpillar forms of the genera Heliothis, Agrotis, Trichoplusia and Spodoptera.